0634 Surface roughness characterization of current tooth colored filling materials after tooth brushing: an AFM study S.M. MASUDI1, N.S. MASUDI1 and S.I. IRAWAN2 1School of Dental Sciences, Universiti Sains Malaysia, Kubang Kerian, Malaysia 2Stanford University, 450 Serra Mall Stanford, CA 94305, USA. ABSTRACT Objective: Directly placed filling materials have a profound influence on the surface roughness of tooth-coloured restorations. This in vitro study is designed to evaluate the influence of tooth brushing on surface roughness of three different current composite resins and glass ionomer cement. Method:  Eighteen specimens of the restorative materials, nanofilled composite Filtek Z350 XT, the sub-micron composite Estelite Sigma Quick, and nanofilled glass ionomer Ketac N100 were used. Six specimens (2 mm thick and 6 mm in diameter) of each tested material prepared according to the manufacturer's directions. After insertion of the test material, poly Ethylene was applied and the material pressed down with glass slide, obtaining flat surfaces. All samples were then polished using Sof-Lex discs from coarse (55 µm) to medium (40 µm) to fine (24 µm), and ultrafine (8 µm), using a mandrel and a slow-speed hand piece. After polishing, the samples were cleaned ultrasonically using a Sonica 2200 ETH for 5 minutes and then stored in distilled water at 37° C for 24 hours. A brushing sequence of 5000, 10,000 and 20,000 cycles was performed for all the samples. An AFM examination was used to determine average surface roughness (Ra) of the material assessed. The data obtained were analyzed using one-way ANOVAs and post-hoc comparison tests. Result:  Brushing significantly increased roughness (Ra) for all tooth colored filling materials. Statistical significance was declared if the P value was ≤ 0.05. After 5000, 10,000 and 20,000 cycles, Ketac N 100 nano ionomer demonstrated significantly higher surface roughness than the other materials, followed by Estelite Sigma Quick. Filtek Z350 XT showed the lowest value of surface roughness. Surface roughness was increased with each cycle for three materials. Conclusion:  Although the initial performance of three materials was similar, a greater number of brushing cycles generated surface roughness of the materials.   Table 2 Fig. 1a. 3D AFM images showing the topography of Filtek Z350XT (3M-ESPE) b. Estelite Sigma Quick (Tokuyama) and c. Ketac N100 (3M-ESPE) nanoionomer, polished by different polishing protocols (a) (b) increment (Fig. B). All samples were then polished using Sof-Lex discs from coarse (55 µm) to medium (40 µm) to fine (24 µm), and ultrafine (8 µm), using a mandrel and a slow-speed hand piece (Fig. C). After polishing, the samples were cleaned ultrasonically using a Sonica 2200 ETH for 5 minutes and then stored in distilled water at 37° C for 24 hours. A brushing sequence of 5000, 10,000 and 20,000 cycles was performed for all the samples using a tooth brushing simulator. AFM was used to determine average surface roughness (Ra) of the material assessed. Statistical analysis was performed with the Mann-Whitney tests and Kruskal-Wallis with a P value of ≤0.05. INTRODUCTION Composite resin and glass ionomers are the most popular dental restorative materials. They offer superior esthetics, require minimal tooth preparation and are widely used for anterior and posterior restorations.   (c) DISCUSSION PURPOSE A tooth brushing simulator was used to demonstrate surface roughness. It works on programmable brushing number of cycles. AFM gives the quantitative measures of surface irregularities [1]. In the present study, the Filtek Z350 XT had lowest surface roughness values followed by Estelite Sigma Quick . The highest was found in Ketac N 100 nano ionomer. Nanocomposites have small primary filler particles, so that the filler and resin matrix are abraded off together during wear. For microhybrid composites whose average filler particle sizes are ~1 mm, the relatively soft resin matrix is worn first and the inorganic filler stands out above the surface [2]. The aims of this experimental in vitro study is to evaluate the influence of tooth brushing on surface roughness of three different current composite resins and glass ionomer cement. In assessing average surface roughness (Ra) of the material, the atomic force microscopy (AFM) was used for this study. MATERIALS AND METHODS RESULTS Samples were fabricated using plexiglass discs of 6 mm diam. and 2 mm in height covered by polyethylene sheets and pressed with glass glass slides (Fig. A). Six specimens of each tested material prepared according to the manufacturer's directions. Total 18 specimens of the restorative materials, nanofilled composite Filtek Z350 XT, the sub-micron composite Estelite Sigma Quick, and nanofilled glass ionomer Ketac N100 were used. After insertion of the test material, poly Ethylene was applied and the material pressed down with glass slide, obtaining flat surfaces. Nanoionomer were placed into the discs and light-cured for 10” and the other two composites were placed incrementally into the discs and light-cured for 20” after each Table 1. Median roughness number (Ra, μm) and interquartile range of the three tested materials after sequences of tooth brushing cycles. CONCLUSION Although the initial performance of three materials was almost similar, a greater number of brushing cycles generated surface roughness of the materials... Material Initial (Ra) Median (IqR) 5000 cycles (Ra5) Median (IqR) 10,000 cycles (Ra10) 20,000 cycles (Ra20) P Value Filtek Z350 XT 71.67* (10.47) 74.87 (12.73) 77.73 (13.73) 80.43 (14.25) 0.037 Estellite Σ Quick 73.36* (11.76) 76.86 (13.41) 79.26 (17.55) 83.67 (15.84) 0.042 Ketac N100 72.49* (10.31) 78.49 (15.65) 82.85 (12.36) 86.22 (13.79) 0.035 REFERENCES 1. Irawan BA., Irawan SN, Masudi SM.,Sukminingrum S. and Alam MK. (2014).3D Surface Profile and Color Stability of Tooth Colored Filling Materials after Bleaching. BioMed Res Int, Art ID 327289. 2. Irawan B.A., Masudi S.M., Han H.X., Othman N.F., Alam M.K., 2013. In-vitro Computer Analysis of Digital Images on Tooth-Colored Restoraive Material Using L*a*b Values. Int Med J, 20(5), 623-625. Kruskal-Wallis test; P value <0.05 is significant; IqR: Interquartile range,=. *Indicate no significant difference (p>0.05). Research presented at the 93rd General Session & Exhibition of the IADR/44th Annual Meeting of the AADR, March 11-14, 2015